Exemplary embodiments of the present disclosure relate to a disk assembly and a turbine including the same, and more particularly, to a disk assembly disposed between a compressor section and a turbine section in a gas turbine and transferring a rotational torque generated by the turbine section to the compressor section, and a turbine including the same.
A gas turbine is a kind of motor which acquires a rotational force by injecting combustion gas toward blades of a turbine, and may be divided into a compressor, a combustor and a turbine. The compressor serves to receive a part of power generated through rotations of the turbine, and compress introduced air at high pressure, and the compressed air is transferred to the combustor.
The combustor generates a high-temperature combustion gas flow by mixing and combusting the compressed air and fuel, and injects the generated combustion gas toward the turbine. The injected combustion gas rotates the turbine to generate a rotational force.
The compressor and the turbine include a plurality of rotor disks having blades radially coupled to the outer circumference thereof. Typically, the compressor includes a larger number of rotor disks than the turbine. Hereafter, the plurality of rotor disks arranged in the compressor is referred to as a compressor section, and the plurality of rotor disks arranged at the turbine is referred to as a turbine section.
Each of the rotor disks is coupled to an adjacent rotor disk such that the rotor disks are rotated together. Furthermore, the rotor disks are fixed against each other through a tie rod, and thus not moved in the axial direction.
The tie rod may be inserted through the centers of the respective rotor disks, and the rotor disks may be fastened through nuts coupled to both ends of the tie rod, and thus not moved in the axial direction.
Since the combustor is arranged between the compressor section and the turbine section, the compressor section and the turbine section are separated from each other so as to form a space in which the combustor is to be disposed. Since the tie rod restricts only the axial movement of the rotor disks, the rotor disks can be freely rotated about the tie rod. Thus, a torque transfer member must be additionally installed to transfer a rotational torque generated by the turbine section to the compressor section via the combustor.
An example of the torque transfer member is a torque tube. The torque tube has a hollow cylindrical shape, and both ends of the torque tube are coupled to the last rotor disk of the compressor section and the first rotor disk of the turbine section, respectively, such that a torque is transferred therebetween.
The torque tube must be resistant to deformation and distortion, because the gas turbine is continuously operated for a long term. Furthermore, the torque tube must be easily assembled/disassembled in order to facilitate maintenance. Furthermore, since the torque tube also functions as an air flow path through which cooling air supplied from the compressor section is transferred to the turbine section, the cooling air must be able to be smoothly supplied.